How do I find a max value of a signal defined within a range?

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Anonymous45 2017-3-18

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https://ww2.mathworks.cn/matlabcentral/answers/330503-how-do-i-find-a-max-value-of-a-signal-defined-within-a-range

编辑： Anonymous45 2017-3-18

Hello, I am looking for some help please. I have two signals and I am taking the max peak of signal 1, which is for example 3.019 Hz and then I want to create a range by subtracting .05 and adding .05 to 3.019 to create a range of 2.969 Hz to 3.069 Hz. Then I want to use that range to find signal 2's peak between 2.969 Hz to 3.069 Hz. Therefore, I just want to find the peak for signal 2 within that range.

if true
signal = cos(2*pi*f*t).*(A.*(heaviside(t)-heaviside(t-39E-9)));
data1 = zeros(1,1);
index1 = 0;
    y1 = fft(signal);
    m1 = abs(y1);
    er1 = (0:length(y1)-1)*(1/h)/length(y1); 
    indexmax1 = find(max(m1) == m1);
    xmax1 = er1(indexmax1);
    ymax1 = m1(indexmax1);
    index1 = index1 + 1;
    data1(index1, 1:1) = xmax1(1,1);
%Graphed signal_4
signal_4 = [cos(2*pi*f*t).*(A4.*(heaviside(t)-heaviside(t-4E-9)))]+[cos(2*pi*f*t).*(A4.*(heaviside(t-7E-9)-heaviside(t-11E-9)))];
data4 = zeros(1,1);
index4 = 0;
    y4 = fft(signal);
    m4 = abs(y4);
    er4 = (0:length(y4)-1)*(1/h)/length(y4);
    indexmax4 = find(max(m4) == m4);
    xmax4 = er4(indexmax4);
    ymax4 = m4(indexmax4);
    index4 = index4 + 1;
    data4(index4, 1:1) = xmax4(1,1);
end

This is just the skeleton of my code and therefore will not run, but is just to convey what tools I am using to find the peaks.

Basically as I generate more signals the peaks of the other signals get more narrow, but as a result more peak appear some higher then the peaks I want, so that's why I am using signal 1's peak to narrow down signal 2's peak.

Hope this all made sense. Please any help would be greatly appreciated.